1. Field of the Invention
This invention is directed toward the cutting head used in a brush cutter and toward the cutting teeth employed on the cutting head. The invention is also directed toward a brush cutter employing the cutting head.
2. Description of the Related Art
Cutting heads used in brush cutters are known. However the known cutting heads have several disadvantages. One type of cutting head employs cutting teeth that are pivotally mounted, the teeth swinging radially outwardly as the cylindrical support head, carrying the teeth, and the mountings for the teeth, is rotated. Examples of such cutting heads are shown in U.S. Pat. Nos. 5,642,765 and 5,975,167. The pivot mountings for the cutting teeth are however easily damaged and replacement of the teeth, when damaged, can be difficult due to damage to the mountings.
Mounting blocks for the cutting teeth on cutting heads are also often fixedly mounted on the surface of the cylindrical support head in an exposed position. An example is shown in U.S. Pat. No. 5,873,534. These mounting blocks, and/or the teeth fixedly mounted on them, often hit rocks or large trees and are damaged or even broken off. Replacement of these mounting blocks is difficult and expensive.
The cutting teeth on brush cutters are often designed and mounted on the mounting blocks on the cutting head to cut in a tangential direction when the cylindrical support head is rotated. As a result, the mounting blocks are subject to high shear forces. The blocks must be quite large to resist these forces and this adds weight to the cutting head increasing power requirements. The teeth employed are also usually quite complicated in construction, as shown by the cutting teeth in the above patents, and are quite costly to replace when broken or damaged.
The cutting heads are normally mounted on a brush cutter vehicle to have the cylindrical support head, carrying the cutting teeth, rotate in a direction toward the vehicle. The chips and debris produced could damage the vehicle and injure the operator.
It is the purpose of the present invention to provide brush cutting heads which are stronger, less likely to damage, easier to service, and more efficient to operate, than known brush cutters.
It is also a purpose of the present invention to provide improved teeth for a brush cutting head which teeth are relatively simple and inexpensive to manufacture, easy to mount, and easy to replace. It is also the purpose of the present invention to provide a brush cutter with the brush cutting head mounted to minimize damage to the brush cutter.
In accordance with the present invention there is provided a brush cutting head having a cylindrical support base with cutting tooth mounting blocks fixedly mounted on the base. The blocks are preferably arranged in two diametrically opposed lines on the base with the blocks in each row spaced apart and the blocks in one row alternating with the blocks in the other row in a direction parallel to the longitudinal axis of the base. Each block carries a cutting tooth detachably mounted thereon. The block carries the cutting tooth at an acute angle to a radial line passing from the axis of the base to the top, front of the block, the cutting tooth angled toward the direction of rotation of the tooth. The tooth has a front cutting section above the mounting block that is bent forwardly from the remainder of the tooth which remainder is fastened to the block. The front cutting section is angled forwardly at a small acute angle above a tangential line leading from the top, front of the block, transverse to the radial line. Thus the tooth on each block is angled slightly forwardly and upwardly so that reaction forces, when the tooth is cutting, are directed, via the block, down into the base partly via compression rather than all by shear. This arrangement strengthens the blocks and allows relatively lighter blocks to be used.
Protective means are provided in front of each mounting block to prevent the blocks from directly striking rocks or large trees during operation of the cutting head. Thus the blocks are not subjected to sudden large forces which could result in serious damage. The protective means preferably comprise rings encircling the cylindrical support base, a ring aligned with each block and of a height at least equal to the height of the block but lower than the height of the cutting section of the tooth on the block.
The teeth employed on the cutting head can be simply made from plate or strap material, shaped to have a relatively long base section and a relatively short cutting section. The cutting section is bent from the base section to extend thereto at an obtuse angle. The cutting section is tapered toward its free end to provide the cutting edge. Cooperating mounting means on the tooth and block securely mount the tooth on the block in a manner preventing its movement relative to the block.
The brush cutting head is mounted on a boom on a brush cutter to have the longitudinal axis of the cylindrical base parallel with the boom. This permits the head to operate in a manner that directs chips and debris in a direction transverse to the brush cutter vehicle, and the operator on the vehicle, thereby minimizing damage and injury.
The invention is particularly directed toward a brush cutting head having a cylindrical, tubular, support base and a plurality of cutting tooth mounting blocks fixedly mounted on the cylindrical outer surface of the base, the blocks extending transverse to the longitudinal axis of the base, each block having a front face. A cutting tooth is detachably mounted on each block. Each cutting tooth is made from a plate-like member having a relatively long base section and a relatively short cutting section bent from the base section. The tooth is mounted on the block with the base section adjacent the front face and with the base section extending outwardly from the base. The cutting section is located above the block and extends forwardly from the base section.
The invention is also directed toward a cutting tooth for a brush cutting head made from a plate having a uniform thickness with an inner surface and an outer surface. The tooth has a straight, relatively long, base section and a straight, relatively short, cutting section. The cutting section is bent from one end of the base section, toward the inner surface, to form an obtuse angle between the inner surface of the base section and the inner surface of the cutting section.
The invention is further directed toward a brush cutter having:
a brush cutting head having a cylindrical, tubular, support base; a plurality of cutting tooth mounting blocks fixedly, mounted on the cylindrical outer surface of the base, the blocks extending transverse to the longitudinal axis of the base; a cutting tooth detachably mounted on each block; each cutting tooth made from a plate-like member having a relatively long base section and a relatively short cutting section bent from the base section; the tooth mounted on the block with the base section to have the base section extending outwardly from the base and the cutting section above the block and extending forwardly from the base section;
a narrow holder for the brush cutting head, the holder rotatably mounting the head at the bottom of the holder with the head aligned with the holder, and drive means on the holder for rotating the head;
and a vehicle having a boom, the holder pivotably mounted, at one end, on the end of the boom and aligned with the boom, the holder remaining aligned with the boom when pivoted relative to the boom.